Well, when I used the debug method it connected perfectly and took less than a minute.
Last night after I posted initially about the issue I tried it again three times and each time the job list screen showed the jobs taking at least four and a half minutes, and once was just a couple of seconds under five minutes.
Since this faster connection was using the debug method I'll try again without. Something else it's started doing is not recognizing the device at all. I have to unplug it and plug it in again. I did try restarting my computer and Calibre when this behavior is exhibited but it doesn't seem to affect anything.
Okay, tried it again without debug. The first time it didn't recognize the device at all. Second time [after unplugging and reconnecting] it took about a minute and a half to know that the device was there and then was pretty fast with the jobs. Well under the five minutes it's been taking, but still around two minutes by the time it sees the device and then processes the jobs. That still is much better than the five minutes I was dealing with yesterday.
Since I hadn't tried to connect this morning before trying the debug I can't speak to anything that would have made a difference of this sort with the connection time. Nothing had changed since last night so it's a bit of a mystery. Thanks for your help.